1. Field of the Invention
This invention relates to a process for making polymers, and, more particularly, to a solution polymerization process for making polymers of a vinyl lactam, a polymerizable carboxylic acid, and, preferably, a hydrophobic monomer, which is provided as a stable composition in an alcohol-water solvent having a residual vinyl lactam content of less than 500 ppm.
2. Background of the Invention
Polymers of a vinyl lactam, preferably vinyl pyrrolidone, a polymerizable carboxylic acid, preferably acrylic acid or methacrylic acid, and, optionally, a hydrophobic monomer, preferably a long chain alkyl (C.sub.8 -C.sub.24) acrylate, methacrylate, acrylamide or methacrylamide, have been prepared by solution polymerization in ethanol, or precipitation polymerization in heptane. However, such processes usually leave some residual vinyl lactam monomer. Since such terpolymers are used as hair spray fixatives it is desired to reduce the residual vinyl lactam content to commercially acceptable levels.
Accordingly, it is an object of this invention to provide a solution polymerization process for making polymers of a vinyl lactam, a polymerizable carboxylic acid and, optionally, a hydrophobic monomer, which are provided as a stable composition in an alcohol-water solvent having a residual vinyl lactam content of less than 500 ppm.